Turbine air inlet heating and cooling systems generally use a cold/hot water coil or a similar type of heat exchanger to treat the incoming air to the desired temperature. For example, incoming air may be heated in cold ambient conditions so as to provide efficient part loading of the overall gas turbine system and for other purposes. This heat generally may be system waste heat with sufficient energy content or heat from an external source.
Although a power plant often produces a significant amount of waste heat, this heat is often low grade and/or non-recoverable because it is at or below the temperature of the condensate of the bottoming Rankine cycle. As a result of the relatively low overall energy content, this low grade waste heat generally may be vented or otherwise disposed of.
There is therefore a desire for improved waste heat recovery systems and methods. Such systems and methods preferably can recover relatively low grade waste heat for use in systems such as inlet air heating systems so as to improve overall system output and efficiency.